262 
THE HERTER LECTURES. 
I. SPIROCHAETOSIS. 
LECTUEE DELIVERED ON THE HERTER FOUNDATION, JOHNS 
HOPKINS UNIVERSITY, BALTIMORE, MARYLAND, U. S.A., 
8 OCTOBER, 1912. 
By GEORGE H. F. NUTTALL, M.A., M.D., Ph.D., Sc.D., F.R.S. 
Felloiv of Magdalene College; Quick Professor of Biology, Cambridge. 
Under the term “ Spirochaetosis ” are included those diseases of 
man and animals due to the spiral microorganisms known as 
spirochaetes. I shall confine myself to those which produce blood 
infection—the relapsing fevers—in which a remarkable periodic increase 
and decrease in the number of the spirochaetes is observable corre¬ 
sponding to alternating rises and falls of the host’s body-temperature. 
Authority is divided as to whether the spirochaetes are Protozoa or 
Bacteria, and the matter is a fruitful theme of discussion upon which 
I shall not enter here. Judged, however, from their pathological effects 
and their prompt reactions to immune sera and certain drugs, they 
show a pronounced affinity to Protozoa and exhibit phenomena not 
hitherto observed in Bacteria. 
As in trypanosomiasis, spirochaetosis is readily induced by inocula¬ 
tion with infected blood, and may thus be communicated almost 
indefinitely from animal to animal. In one series, for instance, I 
transmitted S. duttoni, with apparently undiminished virulence, through 
100 mice. Again, as in trypanosomiasis {T. leivisi, T. evansi), infection 
may take place by feeding. 
Tramsmission of Spirochaetes by Arthropods. 
Investigations conducted during the last few years have demonstrated 
conclusively that the blood-inhabiting spirochaetes are, in a number of 
instances, transmitted by blood-sucking Arthropods, and I propose to 
deal chiefly with these results since they are of great practical importance 
to preventive medicine. 
